There's a lot of confusion about how to set a title for the terminal tab, particularly using gnome-terminal.

Firstly, gnome-terminal must be told to allow changing the title. That's set in Edit -> Profile Preferences on the "Title and Command" tab. I use "replace initial title" because I typically have a lot of tabs open and it's far too long otherwise.

Next, bash uses a environment variable called PROMPT_COMMAND that updates the window title every time the prompt is displayed. Many times people seem to be setting the title successfully, but then the PROMPT_COMMAND is run and it resets their changes.

Anyway, I want to set the title to a custom variable, say TITLE, if present. Otherwise, I still want to have the username@host:pwd format. To accomplish that, I have added this to my .bashrc:

PROMPT_COMMAND=/home/mike/bin/prompt_command

function title {
export TITLE="$*"
}

With that I can run my own script. Here's an example script:

#!/bin/bash

if [ "x$TITLE" = "x" ]; then
    echo -ne "\033]0;${USER}@${HOSTNAME}: ${PWD}\007"
else
    echo -ne "\033]0;${TITLE}: ${PWD}\007"
fi

After setting that, I can simply run title some short description to help remind me what that tab was doing.